Engine safety switch



Nov. 14, 1950 L. w. MADDox .2,529,775

ENGINE SAFETY SWLTGH Filed Jan. 2o, A1942s Patented Nov. 14, 1950 f 2,529,775 ENGINE SAFETY SWITCH Lewis W. Maddox, Clarksville, Ga., assignor of one-half to Clyde Owen, Atlanta, Ga.

Application January 20, 1948, Serial No. 3,222

1 Claim.

This invention relates to engine safety devices, and more particularly to an oil pressure controlled automatic switch for controlling the ignition of an internal combustion engine.

It is well-known that an internal combustion engine requires a predetermined amount of lubrication of the pistons and cylinders, bearings and other Working parts, or the cylinders become scorched, the bearings burn out and other damage is caused to the engine. Despite the Wide knowledge of this fact, it is not uncommon for an operator to neglect checking and refilling or replacing the oil in his engine.

Therefore it is an object of the present invention to provide a safety device for an engine that will positively indicate a dangerous condition of the oil in the engine.

It is another object of the invention to pro-vide an engine safety device that is operated by the oil pressure of the engine.

lt is still another object of the invention to provide an oil pressure operated engine safety device that controls the ignition of the engine.

It is a further object of the invention to provide an engine safety device having simplicity of design, economy of construction and efficiency of operation.

The novel features that are considered characteristic of the invention are set forth with particularity in the appended claim. rThe invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawing in which an engine system is diagrammatically illustrated and the safety device of the present invention is shown in crosssection.

Referring now to the drawing, an internal combustion engine system is diagrammatically illustrated as comprising an engine block B containing the cylinders, pistons and crankcase, spark plugs P on the block B for firing the cylinders, a distributor D connected to the plugs P by lines L, a coil C connected by a wire X to the distributor D and receiving power by a wire Y from a battery or generator G. The cylinders and bearings in the crankcase are lubricated by oil supplied under pressure from an oil pressure system O through a supply pipe S and withdrawn or exhausted from the block B through the pipe E back to the pressure system O. The engine system set forth in the foregoing description is of conventional design and forms no part of the present invention per se.

20o-sie) According to the present invention, a safety device I is installed in the oil supply line S which feeds oil under pressure from the pressure system O to the engine B, or any other line containing oil under pressure, and this safety device I is connected with the coil C to control the ignition system of the engine B. Specifically, the safety device I comprises a vertically disposed housing 2, preferably tubular, having plugs 3 and 4 connecting it with the supply line S at the bottom and top, respectively. The plugs 3 and 4' have passages 5 and 6 extending axially therethrough for communication between the pipes forming the line S and the chamber I within the housing 2.

The housing 2 has diametrically disposed openings 8 and 9 extending through its walls, a short distance above the bottom plug 3, to receive insulating sleeves il) and I I. Electric wires, or other suitable contacts, I2 and I3 extend through the insulating sleeves II! and I I and into the chamber l in spaced relationship. The wire or contact I2 is connected by a cable Ill with the coil C and the wire or contact I3 is connected by a cable I5 with a ground I6 which may be any grounded portion of the engine system such as the supply line S.

A ball or other suitable conducting member Il is freely positioned in the chamber l. The ball Il should be of a size that is sufficient to substantially close the passage 5 and to span the distance between the spaced contacts l2 and I3. The top plug 4 has a nozzle-like extension IQ protruding down and slightly into the chamber l and the end of this extension is provided with axial slots I8 extending diametrically therethrough for communication with the passage E.

In the operation of the invention, when the ball Il is at rest in the bottom of the chamber l, as shown in the drawing, it completes a circuit between the space contacts l2 and I3 to short circuit the ignition system from the coil C through the cable I4, contact I2, ball Il, contact I3, cable I5 and ground I6, and thereby cut off the engine B.

Upon starting, however, the starter (not shown) turns over the engine B and starts operation of the oil pressure system O to pump oil under pressure through the supply line S to the engine B. When the oil is pumped thro-ugh the line S, it is forced through the passage 5 into the chamber 'I and out through the passage t to the engine B. rThe ow of the oil from the passage 5 forces the ball Il upwardly in the chamber l and thereby breaking the short circuit through the contacts I2 and I3.

Obviously, therefore, if the supply of oil is suflicient in quantity to produce the pressure necessary, it will lift the ball Il, cutting out the short circuit and permitting the operation of the ignition system. If however, the oil decreases in quantity to a dangerous degree, it is incapable of producing sui'licient pressure to lift the ball l1, and, consequently, the ignition system is short circuited so that the engine cannot be operated. The weight of the ball Il should be regulated in accordance with the quantity of oil required for the particular engine.

If the oil pressure is suiiicient, the ball I1 may be forced upwardly against the plug 4 and might possibly close the passage 6. The extension plug I9 precludes this danger, however, having rounded edges that tend to cam the ball laterally, away from the passage G. Furthermore, even if ,the ball seals the mouth of the passage, the `oil may freely by-pass the ball through the slots I3. In addition, if the passage .6 is of a size that might be entered and yjammed by the particular ball, one Vor more of the lips of the extehsionbetween tlije slots iS maybe bent inwardly to restrict the free opening 'of the passage 6.

Although a certain specific embodiment of the invention has been shown and described, it is obvious that many modifications thereof are possible. For instance, the body 2 may be formed of an insulating thermo-plastic material in which event the insulating sleeves Il) and Il may be dispensed with. The invention, therefore, is not to be restricted exceptV insofar as is necessitated by the prioi` art and by the spirit of the appended claim'.`

That which is claimed as new, is: u u A safety switch of the type inserted within the oil pressure and ignition lines of an internal combustion engine foryshortcircuiting the ignition line upon lack of suiiicient pressure in the oil line,

which Vswitch comprises a cylindrical tube that y has integral threads at both the top and ibottom ends thereof, the threads at the top being internal threads, an inlet plug threaded to the threads at the bottom of said tube and having an axial bore for admitting oil from the pressure line, an outlet plug threaded into said internal threads of the top of said tube and having an axial bore for exhausting oil to the pressure line, a metal ball of a diameter substantially larger than said bores and freely enclosed within said tube to be selectively movable against said plugs to seal the bores therein, spaced electric contacts extending inwardly from the sides and in the bottom portion of said tube to be bridged by said ball when it moves against the inlet plug and is at rest, an integral extension onthe bottom of said outlet plug and depending into said tube, said extension surrounding th'e bore in said outlet plug and having a diameter that is smaller than the diameter of the interior of said tube, and radial slots in the bottom of said extension and extending from 'plug bore to the periphery of said extension to bye'pass oil around said ball when the ball is forced by bi1 pressure against said extension and seals the bore therein. A ,Y

LEWIS W. MADDOX'.

REFERENCES CITED The following references are of record in the le of this pia-tent:

U'NTED STATES PATENTS Number ame Date 1,132,791 Pagand 11 Mar. v23, 1915 1,347,019 Edwards 1 July 20, A1929 2,222,542 RObiSOrl NOV. 19, 1940 FOREIGN PATENTS Number Country Date 670,807 France a Oct. 24, 1929 

